Superoxide dismutase activity will be determined in lenses from animals subjected to various procedures expected to affect such activity: aging, hyperoxia, aminotriazole, alpha-tocopherol, UV light, etc. Superoxide dismutase levels will be compared: in dogs (which are cataract prone) and cats (which rarely develop cataracts); in flying squirrels which are nocturnal animals with unpigmented lenses and in gray squirrels which have pigmented lenses and are diurnal; in chickens which have no glycogen in the nucleus and in pigeons which have much glycogen.